The present invention relates to the novel compound 2,3-dichloro-5-iodopyridine and to methods of making it. The present invention also relates to 2,3-dichloro-5-lithiopyridine and 3-chloro-5-iodo-2-pyridinol, which are novel intermediates used in preparing 2,3-dichloro-5-iodopyridine, and to the methods of preparing these intermediates.
Japanese Patent Application No. Sho-52-86636 discloses 2-(4-(5-iodo-2-pyridyloxy)phenoxy)propionic acid compounds and derivatives thereof which are used in the preparation of 2-(4-(5-trifluoromethyl-2-pyridyloxy)phenoxy)propionic acid and derivatives which are valuable herbicides. No methods of preparing the iodopyridyloxyphenoxypropionates are disclosed.
British Patent Specification No. 1,599,121 discloses methyl .alpha.-[4-(3-chloro-5-iodo-2-pyridyloxy)phenoxy]propionate (page 14, lines 14 and 15) but does not teach how to make this compound.
Heretofore, 2,3-dichloro-5-iodopyridine has not been disclosed. Initial attempts to prepare 2,3-dichloro-5-iodopyridine employing standard iodinating techniques by iodinating the reactive 5-position of 2-aminopyridine or 2-pyridinol and thereafter chlorinating the 3-position failed to produce this compound. It was not until the methods described herein were employed, that 2,3-dichloro-5-iodopyridine was produced.